These are just some of the explanations offered for the strange noises being heard in the skies all over the world. Yup, not just here in the good ol’ U.S. of A., where Roswell has become a household name. Nope, but rather a far off land known as THE PLANET EARTH.

Reports of these noises began in 2011, but since the new year began, tons of videos have been appearing online capturing the mysterious sounds. We first caught wind of it on The FW and have been intrigued ever since.

The reason for our curiosity is simple: we still have no idea what the heck those noises could possibly be. Some sound like a train rumbling in the distance while others sound straight out of War of the Worlds (the Tom Cruise version). They all have a distinctive electric “mechanical” humming sound.

To make things even creepier, there’s typically nothing in the vicinity to explain the noise. It just sort of drops down from the sky.

What could it possibly be? Let us know what you think in the comments below.